Metallurgical furnaces include walking beam type furnaces and pusher type furnaces. The present invention relates to an improvement in the insulation for a walking beam type of furnace.
Walking beam furnaces include support beams which extend horizontally in the heated furnace area and beams that are supported on legs extending upward through the lower surface of the furnace and such legs are actuated so that the legs are raised so that their beams engage the work pieces within the furnace and move them progressively along the furnace a preselected distance in the direction toward the outlet. The movement of the legs is preferably timed so that the legs are in motion only a small portion of the time and when not in motion the legs are positioned in their retracted position so that their first action is to extend upwardly in the furnace to engage the work pieces.
U.S. Pat. Nos. 3,544,094, 3,471,134, 4,330,262 and 4,585,411 disclose walking beam furnaces which have been known prior to the present invention. U.S. Pat. No. 2,592,236 discloses a walking beam furnace in which the opening in the lower furnace wall through which the legs move is provided with plates through which the legs extends and which are mounted in any suitable fashion so that they are slidable along the bottom of the furnace to cover the openings in any adjusted position of the legs. This is stated to be an attempt to control the large volumes of air which are drawn into the furnace through these openings. The disadvantage of such plates is that in metallurgical furnaces such plates will only last a very short time and then will burn through to allow the air flow through the openings and possibly due to warping cause resistance to the movement of the legs.